laser rifle, power armour and a couple of grenades for everyone is the strategy I used in the old XCOM game, saving that e-115. The lasers were light so movement range was increased, cheap, profitable and they were good for RF too. Laser Rifles in the hands of veterans were deadly from great distances. Once lots of spare stores and soldier stats were built up I might switch to heavy plasmas which weighed about the same as an AR, IIRC and were fairly necessary for the endgame or leaders.
In UFOAI, I'm not sure yet, i think the grenade launchers are good but I really like the flame throwers. tbh, I haven't been able to play through yet, it seems much harder than XCOM, which is a good thing as XCOM got a bit tedious when you were forced to defend or attack a base every 2 minutes toward the endgame or else lose support. Going through the motions, clearing the huge maps and looking for the last hider which could take hours if done properly. For those who don't remember the game, it was scary to lose soldiers and the battlescape no save bug made it even more so. Its a shame there wont be any attacking the commander from a newly created hole in his wall though. You just had to love firing that blaster around corners and then dumping as much HE as you could through the hole and waiting for the screams.
The best tactic I've found is to keep covered. Dont get into a shoot-out with ET, sneak up on him, snipe him or explode him but don't be standing in his sight, or near him at the end of your turn without proper RF cover. I like to jump in to a building, take a shot at ET and run out. His turn, he comes out to shoot back and 2 others, with flame throwers are waiting against the wall with full TU and already facing the door (at a right-angle of fire to avoid the embarrassment of melting your comrade) resulting in a well done alien and any friends standing behind him.
I do like the auto battle feature but I think there should be a trade between the outcome odds and the value of goods recovered. Perhaps making you fight for earning money or allowing the skipping of battles relatively safely; precision airstrikes to kill the menace with no ufo or item recovery for example. This would alleviate some of the aforementioned tedium, IMO leaving the balance up to the player.
There used to be some decent strategy guides about for XCOM which would be largely applicable here.